Adapted from Room for Dessert, David Lebovitz
One 9-inch cake: 12 to 14 servings
Ingredients
½ pound (2 sticks) unsalted butter
12 ounces best quality bittersweet chocolate (I recommend Valrhona 72% )
6 eggs
1 cup sugar
Instructions
Position the oven rack in the center of the oven. Preheat to 350°F. Butter a 9×2-inch round cake pan and line the bottom with parchment paper.
Set a bowl over a pan of simmering water to create a double-boiler. Cut the butter and chocolate into pieces. Melt the butter in the double-boiler, then stir in the chocolate, whisking occasionally until the chocolate is melted. Let the mixture cool to room temperature.
In another bowl, whisk together the eggs and sugar, then thoroughly whisk in the melted chocolate mixture.
Pour the batter into the prepared cake pan. Place it in a larger baking pan and pour warm water to reach halfway up the sides of the cake pan, creating a water bath. If you set the cake pan on a piece of wet paper towel, it will keep it from sliding around as you create the water bath and put the pan in the oven.
Cover the cake tin tightly with foil and bake in the water bath for 1 hour and 15 minutes, until the cake appears to have set, and a toothpick inserted in the center comes out clean. The cake will just be beginning to pull away from the sides of the pan.
Remove the tin from the water bath and cool completely before serving.
Lebovitz suggests serving this cake plain or with crème anglaise. I prefer it with lightly whipped cream.